The present invention relates to a wind power device disposed on the ground.
A conventional wind power system which has high efficiency and simple structure comprises two or three blade wheels which are rotatable around a horizontal axis and are pivotable around a vertical axis so that the blade wheel may always be perpendicular to the wind by suitable means.
The blade wheel is rotated by wind velocity at speed depending on diameter and shape of the blade and its pitch to drive a generator, so that wind power is converted into electric energy.
The blade wheel is rotated by low-density air flow. Even if diameter and area of the blade wheel are increased at maximum, about 45% of wind power energy which passes through the blade wheel is merely collected as useful energy actually.